Why does the site skew so heavily female? It has to do with the difference in male and female brain chemistry.

E-commerce consultant Zoovy explains that males get a hit of happiness-inducing dopamine to the brain upon the completion of a task whereas females get a continuous stream of dopamine throughout the task.

In other terms, males are neurologically rewarded for hunting while females are neurologically rewarded for gathering.

As a social pinboard site, Pinterest is the perfect platform for gatherers.

Furthermore, there's no "end" to Pinterest -- no way to win or beat it as if it were a game. You simply keep pinning, so females are more inclined to stay active.